Multimode antenna feed system for an x-band monopulse radar

In this paper, a 3-channel multimode feed system for a dielectric loaded E-plane rectangular waveguide horn antenna is proposed. A detailed modal analysis for this multimode monopulse feed system is presented. Simulations for the complete system are performed to optimize isolations between sum, azimuth and elevation channels and enhance the matching of each, within a wideband of operation. The feed system exhibits very good amplitude and phase control of the radar signals over a 10-percent bandwidth. Measurements for different target positions in the 9-10 GHz frequency range are carried out to verify the modal analysis and the simulation results. Good agreement between measurements and simulations is achieved.